Polymerization product from cyanate functional maleimide

ABSTRACT

Thermoset products are prepared by polymerizing (A) at least one thermosettable compound which contains both a maleimide group and a cyanate group such as 3-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)phenyl cyanate and optionally (B) at least one of (1) at least one aromatic polycyanate such as bisphenol A dicyanate; (2) at least one polymaleimide such as N,N&#39;-(methylenedi-p-phenylene)bismaleimide; (3) at least one material having an average of more than one vicinal epoxide group per molecule such as diglycidyl ether of bisphenol A; (4) at least one polymerizable ethylenically unsaturated material such as styrene; or (5) a mixture of any two or more of components 1-4 in any combination.

CROSS-REFERENCE TO RELATED APPLICATION This is a divisional, ofapplication Ser. No. 782,644, filed Oct. 1, 1985, now U.S. Pat. No.4,683,276. BACKGROUND OF THE INVENTION

This invention pertains to thermosettable compositions whichsimultaneously contain both a maleimide group and a cyanate group.

Aromatic polycyanates which are thermosettable to polytriazines areknown, for example, from U.S. Pat. Nos. 3,448,079; 3,553,244; 3,694,410;3,740,348; 3,755,402; 4,094,852 and 4,097,455. Said polytriazinespossess excellent heat resistance, however, an improvement in theirmechanical properties, especially tensile strength and elongation wouldbe desirable. Furthermore, there is substantial room for improvement inthe moisture resistance of said polytriazines.

Polymaleimides which are thermosettable are known, for example, fromU.S. Pat. No. 2,444,536 and from New Industrial Polymers, Rudolph D.Deanin (editor), ACS Symposium Series 4 published by American ChemicalSociety, Washington, D.C. (1972), pages 100-123. Said polymaleimides aretypically difficult to process and cure due to high melting points, poorsolvent solubility and slow curing rates. The thermoset (cured)polymaleimides are very brittle and thus of limited utility.

Copolymerization products of compounds containing two or more maleimidegroups with compounds containing two or more cyanate groups are alsoknown, for example, from Proc. Electr./Electron. Insul. Conf., 1981,15th, pages 168-171. Representative of said copolymerization products isthe bismaleimide-triazine resin prepared by copolymerization ofbisphenol A dicyanate and N,N'-(methylenedi-p-phenylene)bismaleimide.Preparation of said copolymerization products always requires premixingor contacting together two separate components: the polycyanate compoundand the polymaleimide compound.

The present invention provides novel compositions which simultaneouslycontain both a maleimide group and a cyanate group. Said compositionsare thermosettable to useful polymeric (cured) compositions includingcastings, laminates, coatings and the like. Many of -he compositions ofthe present invention possess improved mechanical properties andimproved moisture resistance when compared to the polytriazines of theprior art. In addition, improved processability is inherent to thecompositions of the present invention.

SUMMARY OF THE INVENTION

One aspect of the invention concerns a composition which comprises atleast one thermosettable compound which simultaneously contains both amaleimide group and a cyanate group.

Another aspect of the present invention concerns the product resultingfrom polymerizing the aforesaid composition.

A further aspect of the present invention concerns a composition whichcomprises

(A) at least one thermosettable compound which simultaneously containsboth a maleimide group and a cyanate group and

(B) at least one of

(1) at least one aromatic polycyanate;

(2) at least one polymaleimide;

(3) at least one material having an average of more than one vicinalepoxide group per molecule; or

(4) at least one polymerizable ethylenically unsaturated material;

wherein component (A) comprises from about 1 to about 99, preferablYfrom about 1 to about 75, most preferably from about 5 to about 50percent by weight of the combined weight of components (A) and (B).

An additional aspect of the present invention concerns the productresulting from copolymerizing the aforementioned composition.

DETAILED DESCRIPTION OF THE INVENTION

Suitable compositions which simultaneously contain both a maleimidegroup and a cyanate group include, for example, those represented by theformulas ##STR1## wherein each R and R¹ is independently hydrogen or ahydrocarbyl group having from 1 to about 3 carbon atoms; each R' isindependently hydrogen, a hydrocarbyl or hydrocarbyloxy group havingfrom 1 to about 10, preferably from 1 to about 4 carbon atoms, halogen,preferably chlorine or bromine; A is a divalent hydrocarbon group havingfrom 1 to about 10, preferably from 1 to about 4 carbon atoms, --O--,##STR2## --S--, --S--S--, ##STR3## n has a value of zero or 1 and x hasa value of 4.

The term hydrocarbyl as employed herein means any aliphatic,cycloaliphatic, aromatic, aryl substituted aliphatic or aliphaticsubstituted aromatic groups. Likewise, the term hydrocarbyloxy groupmeans hydrocarbyl group having an oxygen linkage between it and theobject to which it is attached.

Particularly suitable compositions which simultaneously contain both amaleimide group and a cyanate group include, for example,4-(1-(3-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)phenyl)-1-methylethyl)phenylcyanate;4-(1-(4-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)phenyl)-1-methylethyl)phenylcyanate;4-(1-(4-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)phenyl)ethyl)phenylcyanate; 4-(4-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)phenoxy)phenylcyanate; 4-((4-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)thio)phenylcyanate; 4-(4-(2,5-dihydro-2,5-dioxo-1yl)benzoyl)phenyl cyanate;4-((4-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)phenyl)sulfonyl)phenylcyanate;4-(1-(4-(2,5-dihydro-3-methyl-2,5-dioxo-1H-pyrrol-1-yl)-1-methylethyl)phenylcyanate;2,6-dibromo-4-(1-(3,5-dibromo-4-(2,5-dihydro-2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)phenyl)-1-methylethyl)phenylcyanate; 4-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)-3-methylphenylcyanate; 4-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)phenyl cyanate and3-(2,5-dihydro-2,5-dioxo-1H-pyarol-1-yl)phenyl cyanate.

The compositions which simultaneously contain both a maleimide group anda cyanate group can be prepared by reacting a stoichiometric quantity ofa maleic anhydride per amine group of a hydroxy(amino)aryl or ahydroxyarylaminoaryl compound in the presence of a suitable solvent thencyanating the resulting hydroxyaryl maleimide product.

Suitable maleic anhydrides include, for example, those represented bythe formula ##STR4## wherein R and R¹ are as hereinbefore defined.

Suitable maleic anhydrides include maleic anhydride, methyl maleicanhydride, mixtures thereof and the like. Most preferred as the maleicanhydride is maleic anhydride, per se.

Suitable hydroxy(amino)aryl and hydroxyarylaminoaryl compounds include,for example, those represented by the formulas ##STR5## wherein R', A, nand x are as hereinbefore defined.

Suitable hydroxy(amino)aryl and hydroxyarylaminoaryl compounds includeo-aminophenol; m-aminophenol; p-aminophenol;2-methoxy-4-hydroxy-1-aminobenzene;3,5-dimethyl-4-hydroxy-1-aminobenzene;3-cyclohexyl-4-hydroxy-1-aminobenzene;2,6-dibromo-4-hydroxy-1-aminobenzene; 5-butyl-4-hydroxy-1-aminobenzene;3-phenyl-4-hydroxy-1-aminobenzene;4-(1-(3-aminophenyl)-1-methylethyl)phenol;4-(1-(4-aminophenyl)-1-methylethyl)phenol;4-(1-(4-aminophenyl)ethyl)phenol; 4-(4-aminophenoxy)phenol;4-((4-aminophenyl)thio)phenol;(4-aminophenyl)(4-hydroxyphenyl)methanone;4-((4-aminophenyl)sulfonyl)phenol and4-(1-(4-amino-3,5-dibromophenyl)-1-methylethyl)-2,6-dibromophenol.

Specific methods for preparing2-(4'-hydroxyaryl)-2-(4'-aminoaryl)propanes suitable for use as thehydroxyarylaminoaryl compound are taught by U.S. Pat. No. 4,374,272which is incorporated herein by reference.

Suitable solvents include aliphatic monocarboxylic acids such as aceticacid, propionic acid, mixtures thereof and the like. Most preferred asthe solvent is acetic acid. The maleamic acid resulting from reaction ofa maleic anhydride and a hydroxy(amino)aryl or hydroxyarylaminoarylcompound, typically in an inert solvent such as chloroform, toluene ordioxane, may be isolated then dehydrated in an aliphatic monocarboxylicacid to the corresponding phenolic functional maleimide. Alternately,the reaction may be performed in a single continuous step in thealiphatic monocarboxylic acid solvent. The product resulting from thisreaction is a phenolic functional maleimide represented by the formulas##STR6## wherein R, R¹, R', A, x and n are as hereinbefore defined.

Compounds which simultaneously contain both the maleimide group and thecyanate group are conveniently prepared by reacting a stoichiometricquantity or a slight stoichiometric excess (up to about 20 percentexcess) of a cyanogen halide with a phenolic functional maleimide, suchas those represented by formulas (Vl) and (VII), in the presence of astoichiometric quantity of a base material.

Suitable cyanogen halides include cyanogen bromide and cyanogenchloride. Alternately, the method of Martin and Bauer described inOrganic Synthesis, Volume 61, pp. 35-68 (1983) and published by JohnWiley and Sons can be used to generate the required cyanogen halide insitu from sodium cyanide and a halogen such as chlorine or bromine.

Suitable bases include both inorganic bases and tertiary amines such assodium hydroxide, potassium hydroxide, triethylamine, mixtures thereofand the like. Most preferred as the base is triethylamine.

Suitable solvents include water, acetone, chlorinated hydrocarbons,ketones and the like. Most preferred solvents are acetone and methylenechloride. Reaction temperatures of from about -40° to about 60° C. areoperable with temperatures of -20° to 25° C. being preferred.

Suitable materials having an average of more than one vicinal epoxygroup per molecule which can be employed herein include, for example,the glycidyl ethers represented by the formulas ##STR7## wherein A, R',x and n are as hereinbefore defined; each A' is independently a divalenthydrocarbon group having from 1 to about 6, preferably from 1 to about 4carbon atoms or a ##STR8## group; p has a value of from zero to about10, preferably from zero to 3; each R" is independently hydrogen or analkyl group having from 1 to about 4 carbon atoms; n' has a value offrom about zero to about 30, preferably from about zero to about 5; n"has a value of from about 0.001 to about 6, preferably from about 0.01to about 3 and x' has a value of 3.

Particularly suitable polyepoxides which can be employed herein include,for example, the diglycidyl ethers of resorcinol, bisphenol A,3,3',5,5'-tetrabromobisphenol A, the triglycidyl ether oftris(hydroxyphenyl) methane, the polyglycidyl ether of aphenolformaldehyde condensation product (novolac), the polyglycidylether of a dicyclopentadiene and phenol condensation product and thelike. The polyepoxides can be used either alone or in combination.

The aforementioned polyepoxides represented by formulas (VIII), (IX),(X), and (XI) can be prepared by reaction of a diphenol or polyphenolwith an epihalohydrin and a basic acting material. Said reactiongenerally involves two distinct steps: coupling reaction of theepihalohydrin and diphenol or polyphenol to provide a halohydrinintermediate and dehydrohalogenation reaction of the halohydrinintermediate to provide the glycidyl ether product. Suitable catalystsand reaction conditions for preparing polyepoxides are described in theHandbook of Epoxy Resins by Lee and Neville, McGraw-Hill (1967) which isincorporated herein by reference.

Suitable aromatic polycyanates which can be employed herein include, forexample, those represented by the formulas ##STR9##

wherein each Z is independently hydrogen, a hydrocarbyl orhydrocarbyloxy group having from 1 to about 4 carbon atoms, chlorine,bromine, or a --O--C.tbd.N group; m has a value of from zero to about100, preferably from zero to about 10 and A, A', R', x, x', n, n" and pare as hereinbefore defined.

Suitable aromatic polycyanates represented by formulas (XII), (XIII),(XIV) and (XV) include, for example, bis-phenol A dicyanate, thedicyanates of 4,4'-dihydroxydiphenyl oxide, resorcinol,4,4'-thiodiphenol, 4,4'-sulfonyldiphenol, 3,3',5,5'-tetrabromobisphenolA, 2,2',6,6'-tetrabromobisphenol A, 3-phenyl bisphenol A,4,4'-dihydroxybiphenyl, 2,2'-dihydroxybiphenyl,2,2',4,4'-tetrahydroxydiphenyl methane,2,2',6,6'-tetramethyl-3,3',5,5'-tetrabromobisphenol A,3,3'-dimethoxybisphenol A, the tetracyanate of2,2'4,4'-tetrahydroxydiphenylmethane. ##STR10## the tricyanate oftris(hydroxyphenyl)methane, the polycyanate of a phenolformaldehydecondensation product (novolac), the polycyanate of a dicyclopentadieneand phenol condensation product, and the like. The aromatic polycyanatesmay be used either alone or in any combination.

The aromatic polycyanates can be prepared by reacting a stoichiometricquantity or slight stoichiometric excess (up to about 20 percent excess)of a cyanogen halide with an aromatic polyphenol in the presence of astoichiometric quantity of a base.

Suitable aromatic polyphenols include, for example, those represented bythe formulas ##STR11## wherein A, A', R', x, x', n, n", m and p are ashereinbefore defined, and each M is independently a hydroarbyl orhydrocarbyloxy group having from 1 to about 4 carbon atoms, chlorine,bromine, a phenyl group or a hydroxyl group.

Suitable cyanogen halides include cyanogen bromide and cyanogenchloride. Alternately, the method of Martin and Bauer described inOrganic Synthesis, Volume 61, pp. 35-68 (1983) and published by JohnWiley and Sons can be used to generate the required cyanogen halide insitu from sodium cyanide and a halogen such as chlorine or bromide.

Suitable bases include both inorganic bases and tertiary amines such assodium hydroxide, potassium hydroxide, triethylamine, mixtures thereofand the like. Most preferred as the base is triethylamine.

Suitable solvents include water, acetone, chlorinated hydrocarbons,ketones, and the like. Most preferred solvents are acetone and methylenechloride.

Reaction temperatures of from about -40 to about 60° C. are operablewith temperatures of -20° to 25° C. being preferred.

Suitable polymaleimides which can be employed herein include, forexample, those represented by the formulas ##STR12## wherein R and R¹are as hereinbefore defined, Q is a divalent hydrocarbly group havingfrom 2 to about 12 carbon atoms and m¹ has a value of 0.001 to about 10;Z¹ is a direct bond, a divalent hydrocarbyl group having from 1 to about5 carbon atoms, --S--, --S--S--, --O--, ##STR13## Typical polymaleimidesrepresented by formulas XV, XVI and XVII include,N,N'-ethylenebismaleimide, N,N'-ethylenebis(2-methylmaleimide),N,N'-hexamethylene-bismaleimide, N,N'-(oxydi-p-phenylene)bismaleimide,N,N'-(methylenedi-p-phenylene)bismaleimide,N,N'-(methylenedi-p-phenylene)bis(2-methylmaleimide),N,N'-(thiodi-p-phenylene)bismaleimide,N,N'-(sulfonyldi-m-phenylene)-bismaleimide,N,N'-(isopropylidenedi-p-phenylene)bis-maleimide, polymethylenepolyphenylene polymaleimides and the like. The polymaleimides may beused either alone or in any combination.

The polymaleimides can be prepared by reacting a stoichiometric quantityof a maleic anhydride per amine group of a polyamine in the presence ofa suitable solvent.

Suitable maleic anhydrides include those previously delineated herein.

Suitable polyamines which can be employed to prepare the polymaleimidesinclude, for example, those represented by the formulas ##STR14##wherein Q, Z¹ and m¹ are as hereinbefore defined.

Suitable polyamines include 1,4-diaminobutane, dodecyl diamine,methylene dianiline, diaminodiphenyl ether,2-methyl-4-ethyl-1,8-diaminooctane, aniline-formaldehyde condensationproducts, mixtures thereof and the like.

Suitable solvents include aromatic hydrocarbons, chlorinatedhydrocarbons, N,N-dimethylformamide and the like. Most preferredsolvents are N,N-dimethylformamide, chloroform and toluene. Thepolymaleamic acid resulting from reaction of a maleic anhydride and apolyamine may be isolated then dehydrated to the desired polymaleimide.Alternately, the reaction may be performed in a single continuous step.Detailed procedures for preparing polymaleimides can be found in U.S.Pat. No. 2,444,536 and U.S. Pat. No. 2,462,835 which are incorporatedherein by reference.

Suitable polymerizable ethylenically unsaturated materials which can beemployed herein include those represented by the formula ##STR15##wherein each Q¹ is independently hydrogen, a hydrocarbyl orhydrocarbyloxy group having from 1 to about 4 carbon atoms, a vinylgroup, an allyl group, chlorine or bromine; each Q² is independentlyhydrogen or a hydrocarbyl or hydrocarbyloxy group having from 1 to about4 carbon atoms; Y¹ is ##STR16## wherein R, R¹ abd R² is independentlyhydrogen or a hydrocarbyl group having from 1 to about 3 carbon atoms;and w and w¹ are each positive integers, the sum of which is 5.

Typically ethylenically unsaturated compounds represented by formulaXXVI include, for example, styrene, alpha-methylstyrene, andchlorostyrene, bromostyrene, t-butylstyrene, p-methylstyrene,p-methoxystyrene, divinylbenzene, propylstyrene,chloro-alpha-methylstyrene, m-methylstyrene, o-methylstyrene,allylbenzene, methallylbenzene, p-allylstyrene, diallylblenzene,mixtures thereof and the like.

Equally preferred as the polymerizable ethylenically unsaturatedmaterial which can be employed include herein the acrylate estersrepresented by the formula ##STR17## wherein R³ is a hydrocarbyl grouphaving from 2 to about 25 carbon atoms and may be branched, cyclic orpolycyclic and R⁴ is hydrogen or a methyl group.

Typical acrylate esters represented by formula XXVII include ethylacrylate, n-butyl acrylate, n-butyl methacrylate, sec-butyl acrylate,2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, n-dodecyl acrylate,cyclohexyl acrylate, methyl cyclohexyl acrylate, norbornyl acrylate,dicyclopentadiene acrylate, methyl dicyclopentadiene acrylate, mixturesthereof and the like.

Although less preferred, any other of the known polymerizableethylenically unsaturated compounds can be employed herein either aloneor in any combination. Typical of these compounds are acrylonitrile,diallylphthalate, vinyl chloride, vinyl bromide, vinyl acetate, vinylnaphthalene, the poly(ethoxy)acrylate of dicyclopentadiene, mixturesthereof and the like.

Composltions which comprise at least one thermosettable compound whichsimultaneously contains both a maleimide group and a cyanate group (I,II) may be cured (polymerized) by heating from 50° to about 350° C. ormore, preferably by heating from 70° to 200° C. and optionally in thepresence of 0.001 to 5 percent by weight of a suitable cyclizationcatalyst. Operable cyclization catalysts include those taught by U.S.Pat. Nos. 3,694,410 and 4,094,852. Most preferred cyclization catalystsare cobalt naphthenate and cobalt octoate. The quantity depends upon theparticular cyclization catalyst, cure time, cure temperature andstructure of the specific compound being cured.

Prepolymerization or B-staging of the compositions can be accomplishedby using lower temperatures and/or shorter curing times. Curing of thethus formed prepolymerized or B-staged resin can then be completed at alater time or immediately following prepolymerization or B-staging byincreasing the temperature and/or curing time.

The cured (polymerized) products prepared from at least onethermosettable compound which simultaneously contain both a maleimidegroup and a cyanate group can posses a complex variety of curingstructures including the cyanate group homopolymerization structure##STR18## the maleimide group homopolymerization structure ##STR19## andcyanate group and maleimide group copolymerization structures such as,for example ##STR20##

Compositions which comprise at least one thermosettable compound whichsimultaneously contains both a maleimide group and a cyanate group (I,II) and at least one compound selected from the group consisting of anaromatic polycyanate, (XII, XIII, XIV, XV), a polymaleimide (XX, XXI,XXII), a polyepoxide (VIII, IX, X, XI) or a polymerizable ethylenicallyunsaturated material (XXVI, XXVII) may be cured (copolymerized) byheating from 50° to about 350° C. or more, preferably from 70° to 200°C. and, optionally, in the presence of 0.001 to 5 percent of a suitablecyclization catalyst and, optionally, 0.001 to 3 percent of a suitablefree radical forming catalyst.

Suitable cyclization catalysts include those previously delineatedherein while suitable free radical forming catalysts include the organicperoxides, hydroperoxides, azo compounds and diazo compounds. Mostpreferred free radical forming catalysts include t-butyl peroxybenzoate,azobisiosbutyronitrile, dicumylperoxide and di-t-butylperoxide. Thequantity depends upon the particular free radical forming catalyst, curetemperature, cure time and the particular compounds being copolymerized.

Prepolymerization or B-staging of the compositions can be accomplishedas was previously described.

The cured (copolymerized) products possess a complex variety of curingstructures which depend, in part, upon the amounts and types ofcompounds being copolymerized, cure time, cure temperature, presence orabsence of a cyclization catalyst, presence or absence of a free radicalforming catalyst and other known variables.

Compositions which contain at least one thermosettable compound whichsimultaneously contains both a maleimide group and a cyanate group (I,II) and either an aromatic polycyanate (XII, XIII, XIV, XV) or apolymaleimide (XX, XXI, XXII) or both can copolymerize to produce theaforementioned curing structures delineated for thermosettable compoundswhich simultaneously contain both a maleimide group and a cyanate group.It should be noted, however, that the relative mole ratio of cyanategroups to maleimide groups can influence the amounts of the variouscuring structures in the cured product. For example, a large excess ofcyanate groups, provided by using an aromatic polycyanate in thecopolymerizable composition, increases the amount of triazine duringstructure in the cured product.

Compositions which contain at least one thermosettable compound whichsimultaneously contains both a maleimide group and a cyanate group (I,II) and a polyepoxide (VIII, IX, X, XI) possess complex curingstructures including those derived from copolymerization reaction of thecyanate group and the glycidyl ether group ##STR21##

Compositions which contain at least one thermosettable compound whichsimultaneously contains both a maleimide group and a cyanate group (I,II) and a polymerizable ethylenically unsaturated material (XXVI, XXVII)can possess curing structures derived from copolymerization reaction ofthe maleimide group and the polymerizable ethylenically unsaturatedgroup, from copolymerization reaction of the maleimide group and thecyanate group, as well as from copolymerization reaction of the cyanategroup and the polymerizable ethylenically unsaturated group.Additionally present may be curing structures derived fromhomopolymerization of the polymerizable ethylenically unsaturatedgroups, from homopolymerization of the maleimide groups, as well as fromhomopolymerization of the cyanate groups.

The terms homopolymerization and copolymerization are also meant toinclude both dimerization and oligomerization.

The compositions which comprise at least one thermosettable compoundwhich simultaneously contains both a maleimide group and a cyanate group(formulas I, II) and at least one compound from the group consisting ofan aromatic polycyanate (formulas XII, XIII, XIV, XV), a polymaleimide(formulas XX, XXI, XXI), a polyepoxide (formulas VIII, IX, X, XI) or apolymerizable ethylenically unsaturated material (formulas XXVI, XXVII)may be copolymerized either simultaneously or in stages.

In a preferred process of the present invention, a thermosettablecompound which simultaneously contains both a maleimide group and acyanate group (formulas I, II) and a polymerizable ethylenicallyunsaturated material are first copolymerized in the presence of 0.001 to2 percent of a suitable free radical forming catalyst and at a suitablereaction temperature while in solution in an aromatic polycyanate(formulas XII, XIII, XIV, XV). Operable free radical forming catalystsare as hereinbefore described. Suitable reaction temperatures are fromabout 65° C. to about 125° C. The compound which simultaneously containsboth a maleimide group and a cyanate group and the polymerizableethylenically unsaturated material may first be mixed to form a solutionwhich is then added to the polycyanate. Alternately, the polymerizableethylenically unsaturated material may be added to a solution of thecompound which simultaneously contains both a maleimide group and acyanate group and the polycyanate. The product resulting from thiscopolymerization is a copolymer of the polymerizable ethylenicallyunsaturated material with the maleimide groups of the compound whichsimultaneously contains both a maleimide group and a cyanate groupdissolved in or mixed with a polycyanate. This product may be cured(homopolymerized) as previously described herein or copolymerized, forexample, with a polyepoxide, as previously described herein.

As a specific example, copolymerization of styrene and3-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)phenyl cyanate in the presenceof a free radical forming catalyst while in solution in bisphenol Adicyanate provides a copolymer of the following structure dissolved inor mixed with the bisphenol A dicyanate: ##STR22## Depending on theamounts of the styrene and3-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)phenyl cyanate used, significantamounts of homopolymer of either of the aforementioned compounds mayalso be present.

In another preferred process of the present invention, a thermosettablecompound which simultaneously contains both a maleimide group and acyanate group (I, II) and a polymerizable ethylenically unsaturatedmaterial are copolymerized in the presence of 0.001 to 3 percent of asuitable free radical forming catalyst and at a suitable reactiontemperature optionally in the presence of an inert solvent. The productresulting from this copolymerization is a copolymer of the ethylenicallyunsaturated material with the maleimide groups of the compound whichsimultaneously contains both a maleimide group and a cyanate group. Thisproduct may be cured (homopolymerized) as previously described herein orcopolymerized, for example, with a polycyanate and/or a polyepoxide, aspreviously described herein.

In those instances where R' is chlorine or bromine (formulas I, II,VIII, IX, X, XI, XV), Z is chlorine or bromine (formulas XII, XIII, XIV,XV) and/or Q¹ is chlorine or bromine (formula XXVI) the halogen(s) areincorporated into the copolymers by the polymerization of monomer(s)containing said group(s). Furthermore, the halogen groups can beincorporated into lhe copolymers in a specific location within thepolymer structure. As a specific example, copolymerization of3-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)phenyl cyanate, bisphenol Adicyanate and chlorostyrene provide a copolymer wherein Q¹ is chlorineand Q¹ is specifically present only on the styrene aromatic rings withinthe polymer chains. Said halogen containing copolymers are useful asfire retardant polymers.

If desired, the compositions can contain fillers, pigments, dyes,reinforcing materials, other additives and the like.

The compositions of the present invention are useful in the preparationof castings, structural or electrical laminates or composites, coatings,and the like.

Laminates or composites can be prepared from the compositions of thepresent invention employing any facing and/or reinforcing materials suchas, for example, metallic sheets, woven or mat materials, such asfiberglass, graphite, asbestos, aramids, carbon combinations thereof andthe like.

The following examples are illustrative of the invention but are not tobe construed as to limiting the scope thereof in any manner.

EXAMPLE 1 A. Synthesis of a Phenolic Functional Maleimide

A 54.57 gram portion of m-aminophenol (0.50 mole) and 650 milliliters ofacetic acid were added to a reactor and maintained under a nitrogenatmosphere with stirring. The stirred solution was maintained at 25° C.,then 49.03 grams of maleic anhydride (0.50 mole) dissolved in 100millili-ers of acetic acid was added to the reactor and heating to 110°C. commenced. The 110° C. reaction temperature was maintained for 14hours (50,400 s), then the product was dried under vacuum by rotaryevaporation at 120° C. for 30 minutes (1800 s) to a dark brown solid.The crude product was extracted with two 250 milliliter portions ofo-dichlorobenzene at 120° C. The combined extracts were maintained at 2°C. for 24 hours (86,400 s) then the light yellow orange coloredcrystalline product was recovered by filtration and dried under vacuumat 60° C. for 24 hours (86,400 s) to provide 35.0 grams ofN-(3-hydroxyphenyl) maleimide. Infrared spectrophotometric analysis of afilm sample of the product confirmed the product structure.

B. Preparation of 3-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)phenyl cyanate

A 34.05 gram portion of N-(3-hydroxyphenyl)maleimide (0.18 mole), 20.02grams of cyanogen bromide (0.189 mole) and 300 milliliters of acetonewere added to a reactor and maintained under a nitrogen atmosphere withstirring. The stirred solution was cooled to -10° C. then 18.31 grams oftriethylamine (0.1809 mole) was added to the reactor over a fifteenminute (900 s) period and so as to maintain the reaction temperature at-5° to -4° C. After completion of the triethylamine addition, thereactor was maintained at -5° to -3° C. for an additional thirty minutes(1800 s), followed by addition of the reactor contents to 1500milliliters of deionized water. After five minutes (300 s), the waterand product mixture was multiply extracted with three 100 millilitervolumes of methylene chloride. The combined methylene chloride extractwas washed with 500 milliliters of 0.05 percent aqueous hydrochloricacid followed by washing with 500 milliliters of deionized water thendrying over anhydrous sodium sulfate. The dry methylene chloride extractwas filtered and solvent removed by rotary evaporation under vacuum for60 minutes at 60° C. 3-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)phenylcyanate (34.25 grams) was recovered in 88.9 percent yield as a light tancolored powder. Infrared spectrophotometric analysis of a film sample ofthe product confirmed the product structure (disappearance of phenolichydroxyl absorbance, appearance of cyanate absorbance at 2232 and 2274cm⁻¹, maintenance of maleimide carbonyl absorbance at 1714 cm⁻¹).

C. Mass Spectroscopic Analysis of 3-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)phenyl cyanate

3-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)phenyl cyanate from B above wasanalyzed by mass spectroscopy using a Finnigan 4500 MS and direct probeintroduction of the sample. Sample ions were observed at the ambienttemperature (150° C.) of the ion source. The molecular ion observed atm/z 214 confirmed the product structure.

EXAMPLE 2 A. Preparation of 4-(1-(4-aminophenyl)-1-methylethyl) phenol

A mixture of 134.0 grams (1.0 mole) of p-isopropenylphenol and 186.0grams (2.0 moles) of aniline was stirred and heated to 150° C. To themixture was added 5.0 grams of a solution obtained by adding 1.28 gramsof 10% hydrochloric acid to 93 grams of aniline and stirring the mixturewell. The reaction was carried out for 3.0 hours (10,800 s) at the 150°C. reaction temperature. The reaction product was cooled to 120° C. then350 milliliters of toluene was added. The product was then cooled to 25°C. and the solid precipitated product was recovered by filtration. Thecrude product was slurried into 350 milliliters of methanol and heatedto a reflux then maintained for 15 minutes (900 s). After cooling, theproduct was recovered by filtration and dried under vacuum to yield4-(1-(4-aminophenyl)-1-methylethyl)phenol as a white powder.

B. Synthesis of a Phenolic Functional Maleimide

A 45.46 gram portion of 4-(1-(4-aminophenyl)-1-methylethyl)phenol (0.20mole) and 500 milliliters of acetic acid were added to a reactor andmaintained under a nitrogen atmosphere with stirring. The stirredsolution was maintained at 25° C., then 19.61 grams of maleic anhydride(0.20 mole) dissolved in 100 milliliters of acetic acid was added to thereactor and heating to a reflux commenced. The 126° C. refluxtemperature was maintained for 15 hours (54,000 s), then the product wasdried under vacuum by rotary evaporation at 100° C. for 60 minutes (3600s). The crude product was dissolved in 250 milliliters ofo-dichlorobenzene at 120° C. and then cooled to 25° C. The light yellowcolored solution was decanted away from a brown colored oil layer anddried under vacuum by rotary evaporation at 100° C. for 60 minutes (3600s) to provide 31.4 grams of4-(1-(4-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)phenyl)-1-methylethyl)phenolas a bright yellow colored powder. Infrared spectrophotometric analysisof a film sample of the product confirmed the product structure.

C. Preparation of4-(1-(4-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)phenyl)-1-methylethyl)phenylcyanate

A 21.70 gram portion of4-(1-(4-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)phenyl)1-methylethyl)phenol(0.1037 mole), 11.53 grams of cyanogen bromide (0.1089 mole) and 250milliliters of acetone were added to a reactor and maintained under anitrogen atmosphere with stirring. The stirred solution was cooled to-5° C. then 10.55 grams of triethylamine (0.1043 mole) was added to thereactor over a eight minute (480 s) period and so as to maintain thereaction temperature at -5° to -3° C. After completion of thetriethylamine addition, the reactor was maintained at -5° to -3° C. foran additional 37 minutes (2220 s), followed by addition of the reactorcontents to 1500 milliliters of deionized water. After 5 minutes (300s), the water and product mixture was multiply extracted with three 100milliliter volumes of methylene chloride. The combined methylenechloride extract was washed with 500 milliliters of 0.05 percent aqueoushydrochloric acid followed by washing with 500 milliliters of deionizedwater then drying over anhydrous sodium sulfate. The dry methylenechloride extract was filtered and solvent removed by rotary evaporationunder vacuum for 30 minutes (1800 s) at 90° C.4-(1-(4-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)phenyl)-1-methylethyl)phenylcyanate (22.2 grams) was recovered in 91.4 percent yield as a lightamber colored oil. Infrared spectrophotometric analysis of a film sampleof the product confirmed the product structure (disappearance ofphenolic hydroxyl absorbance, appearance of cyanate absorbance at 2242and 2271 cm⁻¹, maintenance of maleimide carbonyl absorbance at 1722cm⁻¹).

D. Preparation of Bisphenol A Dicyanate

A 456.60 gram portion of 4,4'-isopropylidene diphenol (2.00 moles),444.91 grams of cyanogen bromide (4.20 moles) and 1,100 milliliters ofacetone were added to a reactor and maintained under a nitrogenatmosphere with stirring. The stirred solution was cooled to -5° C.,then 406.82 grams of triethylamine (4.02 moles) was added to the reactorover a 60 minute (3600 s) period and so as to maintain the reactiontemperature at -5° to -3° C. After completion of the triethylamineaddition, the reactor was maintained at -5° to -3° C. for an additionaltwenty-five minutes (1500 s) followed by addition of the reactorcontents to 1.5 gallons (5.685) of deionized water. After 5 minutes (300s), the water and product mixture was multiply extracted with three 500milliliter volumes of methylene chloride. The combined methylenechloride extract was washed with 500 milliliters of 0.05 percent byweight aqueous hydrochloric acid followed by washing with 500milliliters of deionized water, then drying over anhydrous sodiumsulfate. The dry methylene chloride extract was filtered and solventremoved by rotary evaporation under vacuum for 60 minutes (3600 s) at100° C. Bisphenol A dicyanate (545.8 grams) was recovered in 98.1percent yield as a light tan colored, crystalline solid. Infraredspectrophotometric analysis of a film sample of the product confirmedthe product structure (disappearance of phenolic hydroxyl absorbance,appearance of cyanate absorbance).

E. Preparation and Copolymerization of4-(1-(4-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)phenyl)-1-methylethyl)phenylcyanate and Bisphenol A Dicyanate Solution

A 22.2 gram portion of4-(1-(4-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)phenyl-1-methylethyl)phenylcyanate from C above and 88.8 grams of bisphenol A dicyanate from Dabove were combined and heated to 100° C. with stirring to form asolution. The solution was cooled to 50° C., then 0.11 gram of cobaltnaphthenate (6.0 percent active) was mixed in. This solution wasreheated to 100° C., filtered, then poured into a 1/8 inch (0.3175 cm)mold made from a pair of glass plates and then placed in an oven andmaintained at 125° C. for 2 hours (7200 s), 177° C. for 4 hours (14,400s), 200° C. for 4 hours (14,400 s), then 250° C. for 2 hours (7200 s).The transparent, light amber colored, clear, unfilled casting wasdemolded and used to prepare test pieces for tensile and flexuralstrength, flexural modulus, percent elongation and average Barcolhardness (934-1 scale determinations). Mechanical properties of tensileand flexural test pieces were determined using an Instron machine withstandard test methods (ASTM D-638 and D-790). The results are reportedin Table I.

COMPARATIVE EXPERIMENT A Homopolymerization of Bisphenol A Dicyanate

A 200.0 gram portion of bisphenol A dicyanate prepared using the methodof Example 2-D was heated to 100° C. to form a solution, cooled to 50°C., then 0.20 gram of cobalt naphthenate (6.0 percent active) was added.This solution was reheated to 100° C., filtered, then poured into a 1/8inch (0.3175 cm) mold and cured using the method of Example 2-E. Thetransparent, light amber colored, clear, unfilled casting was demoldedand used to prepare test pieces which were tested using the method ofExample 2-E. The results are reported in Table I.

                  TABLE I                                                         ______________________________________                                                               Comparative                                                       Example 1-E Experiment A                                           ______________________________________                                        Barcol Hardness                                                                            49            48                                                 Tensile Strength,                                                                          13,590/93,701 13,080/90,184                                      psi/kPa                                                                       Elongation, %                                                                              3.12          3.26                                               Flexural Strength,                                                                         22,348/154,085                                                                              19,176/132,215                                     psi/kPa                                                                       Flexural Modulus,                                                                          571,000/3,936,947                                                                           555,000/3,826,630                                  psi/kPa                                                                       ______________________________________                                    

EXAMPLE 3 Copolymerization of 2-Ethylhexyl Acrylate and3-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)phenyl cyanate in a Bisphenol ADicyanate Solution

A 175.0 gram (81.28 percent by weight, pbw) portion of bisphenol Adicyanate prepared using the method of Example 2-D and a 8.0 gram (3.72pbw) portion of 3-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)phenyl cyanateprepared using the method of Example 1-B were added to a reactor andmaintained under a nitrogen atmosphere. The reactor contents were heatedto a 110° C. solution then stirring commenced and dropwise addition of32.29 grams (15.0 pbw) of 2-ethylhexyl acrylate and 0.43 gram ofazobisisobutyronitrile as a solution commenced and was completed over afifteen minute (900 s) period. After an additional 80 minutes (4800 s)of reaction at the 110° C. reaction temperature, the product wasrecovered as a slightly hazy, light amber colored solution. A portion(0.2 grams) of the copoly(2-ethylhexyl acrylate and3-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)phenyl cyanate) in bisphenol Adicyanate solution was analyzed by gel permeation chromatography usingpolystyrene standards. The weight average molecular weight of the2-ethylhexyl acrylate and 3-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)phenylcyanate copolymer portion of the solution was 11,789 and thepolydispersity ratio was 8.98.

EXAMPLE 4 A. Copolymerization of 2-Ethylhexyl Acrylate and3-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)phenyl cyanate in a Bisphenol ADicyanate Solution

A 180.0 gram (80 percent by weight, pbw) portion of bisphenol Adicyanate prepared using the method of Example 2-D and an 11.25 gram (5pbw) portion of 3-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)phenyl cyanateprepared using the method of Example 1-B were added to a reactor andmaintained under a nitrogen atmosphere. The reactor contents were heatedto a 110° C. solution. Then stirring commenced and dropwise addition of33.75 grams (15 pbw) of 2-ethylhexyl acrylate and 0.45 gram ofazobisisobutyronitrile as a solution commenced over a 35 minute (2100 s)period. After an additional 120 minutes (7200 S) of reaction at the 110°C. reaction temperature, the product was recovered as a hazy, lightamber colored solution.

B. Polymerization of Copoly(2-ethylhexyl acrylate and3-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)phenyl cyanate) in Bisphenol ADicyanate Solution

A 210.0 gram portion of copoly(2-ethylhexyl acrylate and3-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)phenyl cyanate) in bisphenol Adicyanate from A above was heated to 50° C., then 0.21 gram of cobaltnaphthenate (6.0 percent active) was added. This solution was heated to100° C., filtered, then poured into a 1/8 inch (0.3175 cm) mold andcured using the method of Example 2-E. The opaque, light amber colored,unfilled casting was demolded and used to prepare test pieces which weretested using the method of Example 2-E. A pair of heat distortiontemperature test pieces were also prepared from the casting and heatdistortion temperature was determined using an Aminco Plastic DeflectionTester (American Instrument Co.) with standard methods (ASTM D-648modified). The results are reported in Table II.

                  TABLE II                                                        ______________________________________                                        Barcol Hardness        36                                                     Heat Distortion Temperature,                                                                         455/235                                                °F./°C.                                                         Tensile Strength psi,kPa                                                                             10,525/72,568                                          Elongation, %          4.49                                                   Flexural Strength, psi/kPa                                                                           17,516/120,769                                         Flexural Modulus, psi/kPa                                                                            422,000/2,909,606                                      ______________________________________                                    

EXAMPLE 5 Polymerization of3-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)phenyl cyanate; Bisphenol ADicyanate and Styrene Solution

A 9.25 gram portion of 3-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)phenylcyanate (4.15 pbw) prepared using the method of Example 1-B; 168.75grams of bisphenol A dicyanate (75.67 pbw) prepared using the method ofExample 2-D; and 45.0 grams of styrene (20.18 pbw) were combined andheated to 100° C. with stirring to form a solution. The solution wascooled to 60° C., then 0.22 gram of cobalt naphthenate (6.0 percentactive) was mixed in. This solution was reheated to 100° C., filtered,then poured into a 1/8 inch (0.3175 cm) mold and cured using the methodof Example 2-E. The transparent, light amber colored, clear, unfilledcasting was demolded and used to prepare test pieces which wereevaluated using the method of Example 2-E. A pair of heat distorliontemperature test pieces were also prepared and tested using the methodof Example 4-B. The results are reported in Table III.

                  TABLE III                                                       ______________________________________                                        Barcol Hardness        51                                                     Heat Distortion Temperature, °F./°C.                                                   379.9/193.3                                            Tensile Strength, psi/kPa                                                                            12,909/89,005                                          Elongation, %          2.81                                                   Flexural Strength, psi/kPa                                                                           18,476/127,388                                         Flexural Modulus, psi/kPa                                                                            522,200/3,600,465                                      ______________________________________                                    

EXAMPLE 6 Homopolymerization of3-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)phenyl cyanate

A portion (1.0 gram) of 3-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)phenylcyanate from Example 1-B, 0.0001 gram of cobalt naphthenate (6.0 percentactive) and 3.0 grams of acetone were thoroughly mixed to form asolution. The solution was devolatilized and then cured using the methodof Example 2-E. A portion (9.54 milligrams) of the resultingtransparent, light amber colored film was analyzed by thermogravimetricanalysis (TGA). Weight loss was recorded as a function of temperature ata 10° C. per minute rate of increase in a stream of nitrogen flowing at35 cubic centimeters per minute. As a comparative experiment, a portion(9.80 milligrams) of the homopolymerized bisphenol A dicyanate ofComparative Experiment A was also analyzed by TGA. The results arereported in Table IV.

                                      TABLE IV                                    __________________________________________________________________________                  Weight Loss %                                                   Sample Designation                                                                          100° C.                                                                    300° C.                                                                    350° C.                                                                    400° C.                                                                    450° C.                                                                    500° C.                                                                    700° C.                          __________________________________________________________________________    Example 6     0   1.0 1.2 17  26.2                                                                              32  49.5                                    Comparative Experiment A                                                                    0.2 1.5 2.0 3.6 30.5                                                                              49  62.2                                    __________________________________________________________________________

EXAMPLE 7

Sets of four flexural strength test pieces prepared from the castings ofExamples 2-E, 4-5 and Comparative Experiment A were weighed, thenimmersed in deionized water contained in individual jars and maintainedat 92° C. The test pieces were weighed at the indicated intervals andthe percent weight gain calculated as follows: 100 [(exposed weight -initial weight)/initial weight]. An average of the percent weight gainwas then calculated. After a total of 94 hours of exposure to the 92° C.deionized water, the flexural strength, flexural modulus and averageBarcol hardness were determined using the method of Example 2-E. Theresults are reported in Table V.

                                      TABLE V                                     __________________________________________________________________________    SAMPLE DESIGNATION                                                                         Example 2-E                                                                            Example 4-B                                                                            Example 5                                                                              Comparative Experiment                __________________________________________________________________________                                            A                                     Flexural Strength, psi/kPa                                                    initial      22,348/154,085                                                                         17,516/120,769                                                                         18,476/127,388                                                                         19,176/132,215                        exposed      17,566/121,114                                                                         15,266/105,256                                                                         18,667/128,705                                                                         19,946/137,524                        percent change                                                                             -21.4    -12.85   +1.03    +4.02                                 Flexural Modulus, psi/kPa                                                     initial      571,000/3,936,931                                                                      422,000/2,909,606                                                                      522,000/3,599,086                                                                      555,000/3,826,614                     exposed      620,000/4,274,776                                                                      411,000/2,833,763                                                                      602,000/4,150,670                                                                      629,000/4,336,829                     percent change                                                                             +8.58    -2.61    +15.33   +13.33                                Barcol Hardness                                                               initial      49       36       51       48                                    exposed      47       35       51       46                                    percent change                                                                             -4.08    -2.78    none     -4.17                                 Percent Weight Gain                                                           24 hours of exposure                                                                       1.64     1.36     0.89     1.93                                  48 hours of exposure                                                                       1.98     1.49     1.04     2.37                                  72 hours of exposure                                                                       2.18     1.57     1.12     2.57                                  94 hours of exposure                                                                       2.28     1.62     1.16     2.69                                  __________________________________________________________________________

COMPARATIVE EXPERIMENT B

A clear, unfilled 1/8 inch (0.3175 cm) casting of abismaleimide-triazine resin (BT 2600 Resin, Mitsubishi Gas Chemical Co.,Inc.) was prepared using the method of Example 2-E with the exceptionthat cobalt acetoacetonate catalyst was used to provide 131 ppm cobaltand curing was completed at 175° C. for 1 hour (3600 s) and 225° C. for2 hours (7200 s). Flexural strength and flexural modulus of test piecesprepared from the transparent, amber colored casting were evaluatedusing the method of Example 2-E. A second set of flexural strength testpieces were prepared and immersed in 92° C. deionized water thenevaluated using the method of Example 7. The results are reported inTable VI and may be compared with the results reported in Example 7.

                  TABLE VI                                                        ______________________________________                                        Flexural Strength, psi/kPa                                                    initial              16,200/111,696                                           exposed              13,130/90,529                                            percent change       -18.95                                                   Flexural Modulus, psi/kPa                                                     initial              673,000/4,640,200                                        exposed              760,000/5,240,048                                        percent change       +12.93                                                   Barcol Hardness                                                               initial              60                                                       exposed              56                                                       percent change       -6.67                                                    Percent Weight Gain                                                           after 24 hours of exposure                                                                         1.31                                                     after 48 hours of exposure                                                                         1.66                                                     after 72 hours of exposure                                                                         1.87                                                     after 94 hours of exposure                                                                         2.04                                                     ______________________________________                                    

I claim:
 1. The product resulting from polymerizing a compositioncomprising at least one thermosettable compound which containssimultaneously in the same molecule only one maleimide or substitutedmaleimide group which groups are represented by the formula ##STR23##wherein each R and R¹ is independently hydrogen or a hydrocarbyl grouphaving from 1 to about 3 carbon atoms; and only one cyanate group. 2.The product of claim 1 wherein said compound is represented by theformulas ##STR24## wherein each R and R¹ is independently hydrogen or ahydrocarbyl group having from 1 to about 3 carbon atoms; each R' isindependently hydrogen, a hydrocarbyl or hydrocarbyloxy group havingfrom 1 to about 10 carbon atoms or a halogen atom; A is a divalenthydrocarbon group having from 1 to about 10 carbon atoms, --O--, --CO--,--S--, --S--S--, --SO--, --SO₂ -- or --O--CO--O--; n has a value of zeroor 1 and x has a value of
 4. 3. The product of claim 2 wherein each R'is independently hydrogen, a hydrocarbyl or hydrocarbyloxy group havingfrom 1 to about 4 carbon atoms or a halogen atom; and when A is presentand is a divalent hydrocarbyl group, it has from 1 to about 4 carbonatoms.
 4. The product of claim 3 wherein said compound is3-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)phenyl cyanate or4-(1-(4-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)phenyl)-1-methylethyl)phenylcyanate.